Sensitivity and Resolution Enhancement of Coupled-Core Fluxgate Magnetometer by Negative Feedback

Coupled-core fluxgate magnetometer (CCFM), which is based on the coupling-induced oscillations in bistable nonlinear dynamics, can achieve self-excitation and obtain superior performances compared with the single core fluxgate magnetometer under the premise of utilizing the same residence times difference readout method. One of the pivotal factors determining the performances of CCFM is the critical coupling factor. To get control of it and further enhance the sensor performances, the negative feedback is exploited and implemented by feeding the magnetization from induction coil to excitation coil of the same fluxgate element (self-feedback). Theoretical analyses, Simulink simulations with a quantitative model, and experimental results obtained in the magnetic shielded environment reveal the critical coupling factor adjustment effect of negative feedback on CCFM and confirm the substantial enhancement of sensor performances. Finally, the sensitivity of CCFM for the static magnetic field detection is improved from 0.0253 to 0.7895 μs/nT, and the magnetic resolution of CCFM is optimized from 0.395 to 0.049 nT. Therefore, the negative feedback is an effective and reliable method for performances enhancement of CCFM, and it has potential utilization on the oscillation systems with similar dynamic peculiarities for factor adjustment.